Nanotubes may be as bad as asbestos

PORTLAND, Ore.  Carbon nanotubes could cause the same maladies as asbestos, according to a study by University of Edinburgh, which also showed that long-thin fibers cause the pathological response known to be a precursor to mesothelioma cancer in mice.

"Long, thin carbon nanotubes showed the same effects as long, thin asbestos fibers," said University of Edinburghprofessor Kenneth Donaldson.

Both carbon nanotubes and asbestos fibers were injected into the abdominal cavity of mice, a technique that is accepted in medical circles as a predictor of how pathogens affect lung tissue. The results showed that like asbestos, long nanotube fibers were thin enough to penetrate deep into lungs, but their length prevented the lungs' built-in mechanisms from removing the particles.

"If nanotubes get into the lungs in sufficient quantity, there is a chance that some people will develop cancer—perhaps decades after breathing it," said Donaldson.

Short nanotubes did not behave like asbestos, and were cleared from the bodies of experimental mice. However, long, thin nanotubes tended to bunch together, causing inflamation and lesions, which are precursors of cancer. Short nanotubes may also be found to cause harm, according to the researchers, who said more research is needed.

Carbon nanotubes have high aspect ratios, only nanometers in diameter but sometimes microns long. Aspect ratios are often over 1000:1. In semiconductors, nanotubes are usually safely affixed to a substrate, but their use in other industries could enable them to enter the water or air where they could become a health hazard.

If nanoparticles are breathed into the lungs, the researchers warned that the health affects would be as severe as breathing in asbestos. Asbestos exposure can cause lung cancer in 30 to 40 years after initial exposure.